In Multi-Protocol Label Switching (MPLS), a P router or Provider Router is a Label Switch Router (LSR) that functions as a transit router of the core network. The P router typically connected to one or more Provider Edge (PE) routers. In conventional embodiments, P routers and PE routers each operate a control plane and a forwarding plane and each of the routers forms a direct adjacency with every other router to which it is directly attached at the IP layer. An important function of the P router transit function is to limit the number of direct IP adjacencies required, by connecting each of the numerous PE routers only to a subset of the much smaller number of P routers, and connecting the P routers to each other. It would be advantageous to eliminate the need for the P routers, but this would require every PE router to form a direct adjacency with many if not all other PE routers. Disadvantageously, the requirement for direct adjacency poses scaling challenges. For example, with thousands of PE routers in an area, the adjacency count per PE router would be of the same order, which is substantially in excess of the adjacency count which can be supported by a conventional router implementation using an embedded control plane. What is needed is an alternative architecture, system, method, and the like replacing the P router architecture enabling scaling and efficiency in operation between PE routers.
Referring to FIG. 1, in a conventional embodiment, an Internet Protocol (IP)/MPLS network 100 is illustrated with PE routers 102 and P routers 104. Here, the PE routers 102 and the P router 104 are interconnected exchanging packets therebetween. Further, the exchanged packets included both control packets and data packets, i.e. there is a control plane 110 and a forwarding plane 120 between the routers 102, 104. In this conventional embodiment, control packets (i.e. the control plane 110) peer with the P routers 104 in a hierarchical arrangement. As described herein, such an architecture can be scaled, but only at the expense of the complexity and cost of preserving the P routers. As an improvement, the concept of a Designated Router (DR) was originally introduced to Link State Routing protocols to reduce the full mesh of control messaging which is otherwise required when multiple routers are connected using an Ethernet LAN segment. In this prior art, the routers attached to the LAN segment determine which of them is best qualified to be the DR, and then all the others form a control adjacency with that DR (and may be a backup DR) and no other routers. In this way, the number of control messages to support routing over the LAN segment is O(N) for N routers, rather than O(N2)/2. However, the DR still poses scalability challenges as all control packets over the control plane 110 must still connect to the DR.